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1.0 Introduction <br />is by means of septic systems and drain fields which may supply additional water to the surface drainage <br />system. Three USGS springs have been identified in the canyon and appear out of fractures between <br />sandstones and shales which outcrop on the surface. Cover is comprised mostly of woodland. Grazing and <br />wildlife are the major land uses. Mining was also a land use with an exhaust shaft and a power substation <br />located in the canyon. Longwall mining panels perpendicular to the direction of flow underlie the canyon. <br />During 1989, a determination was made that the canyon does not meet alluvial valley floor criteria (see <br />Exhibit 30 of the Golden Eagle Permit Document). <br />The geologic setting is an important factor when analyzing hydrology of an area. Stratigraphy in the region <br />ranges in age from Pre-Cambrian to Quaternary. However, only portions of the Raton Formation (see Figure <br />1.1-1) and recent alluvial deposits are exposed in the area of the mine. Most of the formation consists of very <br />fine to medium grained sandstone interbedded with silts[one and shale. Coal that was mined at the Golden <br />Eagle is located near the middle of the Raton Formation. The outcrop of the formation in the azea may be <br />characterized as stream deposits including channel-point bar facies, floodplain deposits and swamp deposits. <br />Alluvial deposits along the Purgatoire River are complex. The headwaters of the river are underlain by <br />volcanic rocks and sediments. As it flows to the east, the river cuts its way through many different geologic <br />formations including Pleistocene glacial-fluvial sediments, foothills belt of Paleozoic-Mesozoic strata, <br />terrestrial sediments of the Tertiary, and marine deposits of the Pierre Shale. Channel shape and structure of <br />the Purgatoire vary within each of these formations as does the water quality. Alluvial deposits in the area of <br />the mines range from their current location to older terraces of forty to fifty feet above the Purgatoire. Buried <br />channels which are incised into the underlying Raton Formation have also been found. Purgatoire River <br />alluvial deposits support typical hydrophytic vegetation characteristic of floodplains and contain groundwater <br />hydrologically connected to the Purgatoire River. The Picketwire Valley of the Purgatoire River alluvial <br />deposits has been designated as an alluvial valley floor and is classified as a renewable resource. <br />Soils are generally shallow and coarse-grained. They are derived from the underlying sandstones and shales. <br />Bedrock exposures are common and scattered throughout the area. The valley bottoms are characterized by <br />alluvial and colluvial deposits which are also coarse-grained and deeper than soils of the mountain slopes. <br />Vegetation varies from riparian and blue grama complexes in the valley bottoms to pinion juniper, oak brush, <br />and pine cover on the side slopes. Vegetation cover ranges from 100 percent in the valley bottoms to none on <br />the steeper side slope rock outcrop areas. <br />The nearest weather station to the mine site is located at the Trinidad Airport (elevation 5,746 feet) <br />approximately 30 miles east. Over a recording period from 1961 to 1990, total annual precipitation averaged <br />13.5 inches. The majority of this precipitation (65%) occurs from May to September. July usually has the <br />most rainfall. The mean annual temperature is 51.8 °F. January is the coldest month with a mean temperature <br />of 32.9 ° F, and July is the warmest month, showing a mean of 60.2 ° F (Owenby and Ezell, 1992). The project <br />area is approximately 1650 feet higher in elevation than the Trinidad Airport and can be considered to have 5 ° <br />Flower mean temperatures and higher average precipitation. <br />Surface water availability is directly related to precipitation received in the drainage. The climate summary, as <br />described in the mine permit document, projects a mean annual precipitation near the mine of 16.92 inches. <br />292-2002 AH Report (Mar.03.03)_rev2 2 <br />